The earliest references to pickled vegetables in East Asia are found in the Chinese Xin Nan Shan 信南山 poem of the Shi Jing (詩經), which uses the character 菹 or 葅 (Korean "jeo", modern Mandarin Chinese "ju1"). The term ji was used until the pre-modern terms chimchae (hanja: 沈菜, lit. soaked vegetables), dimchae, and timchae were adopted in the period of the Three Kingdoms of Korea.[6] The word then was modified into jimchi, and is currently kimchi.

Early kimchi was made of cabbage and beef stock only. Red chili, a New World vegetable not found in Korea before European contact with the Americas, was introduced to Korea from Japan after the Japanese invasions (1592–1598) and became a staple ingredient in kimchi,[7] although its use was not documented until the 18th century.[8] Red chili pepper flakes are now used as the main ingredient for spice and source of heat for many varieties of kimchi. In the twelfth century other spices, creating flavors such as sweet and sour, and colors, such as white and orange, were added.[9]

Kimchi from the northern parts of Korea tend to have less salt and red chilli and usually do not include brined seafood for seasoning. Northern kimchi often has a watery consistency. Kimchi made in the southern parts of Korea, such as Jeolla-do and Gyeongsang-do, uses salt, chili peppers and myeolchijeot (hangul: 멸치젓, brined anchovy allowed to ferment) or saeujeot (hangul: 새우젓, brined shrimp allowed to ferment), myeolchiaekjeot (Hangul: 멸치액젓, "kkanariaekjeot" 까나리액젓, liquid anchovy jeot, similar to fish sauce used in Southeast Asia, but thicker).

Saeujeot (hangul: 새우젓) or myeolchijeot is not added to the kimchi spice-seasoning mixture, but is simmered first to reduce odors, eliminate tannic flavor and fats, and then is mixed with a thickener made of rice or wheat starch (Hangul: 풀). This technique has been falling into disuse for the past forty years.

White kimchi (baek kimchi) is baechu (napa cabbage) seasoned without chili pepper and is neither red in color nor spicy. White radish kimchi (dongchimi) is another example of a kimchi that is not spicy. The watery white kimchi varieties are sometimes used as an ingredient in a number of dishes such as cold noodles in dongchimibrine (dongchimi guksu).

This regional classification dates back to 1960s and contains plenty of historical facts, but the current kimchi-making trends in Korea are generally different from those mentioned below.[11]

Hamgyeong-do (Upper Northeast): Due to its proximity to the ocean, people in this particular region use fresh fish and oysters to season their kimchi.

Hwanghae-do (Midwest): The taste of kimchi in Hwanghae-do is not bland but not extremely spicy. Most kimchi from this region has less color since red chili flakes are not used. The typical kimchi for Hwanghae-do is called pumpkin kimchi (bundi).

Chungcheong-do (Between Gyeonggi-do and Jeolla-do): Instead of using fermented fish, people in the region rely on salt and fermentation to make savory kimchi. Chungcheong-do has the most varieties of kimchi.

Different types of kimchi were traditionally made at different times of the year, based on when various vegetables were in season and also to take advantage of hot and cold seasons before the era of refrigeration. Although the advent of modern refrigeration — including kimchi refrigerators specifically designed with precise controls to keep different varieties of kimchi at optimal temperatures at various stages of fermentation — has made this seasonality unnecessary, Koreans continue to consume kimchi according to traditional seasonal preferences.[14]

After a long period of consuming gimjang kimchi (hangul: 김장김치) during the winter, fresh potherbs and vegetables were used to make kimchi. These kinds of kimchi were not fermented or even stored for long periods of time but were consumed fresh.

Summer radishes and cucumbers are summer vegetables made into kimchi, yeolmu kimchi (hangul: 열무김치) which is eaten in several bites. Brined fish or shellfish can be added, and freshly ground dried chili peppers are often used.

Baechu kimchi is prepared by inserting blended stuffing materials, called sok (literally inside), between layers of salted leaves of uncut, whole Napa cabbage. The ingredients of sok (hangul: 속) can vary, depending on the different regions and weather conditions. Generally, baechu kimchi used to have a strong salty flavor until the late 1960s when a large amount of myeolchijeot or saeujeot had been used.

Traditionally, the greatest varieties of kimchi were available during the winter. In preparation for the long winter months, many types of kimjang kimchi (hangul: 김장 김치) were prepared in early winter and stored in the ground in large kimchi pots. Today, many city residents use modern kimchi refrigerators offering precise temperature controls to store kimjang kimchi. November and December are traditionally when people begin to make kimchi; women often gather together in each other's homes to help with winter kimchi preparations.[15] "Baechu kimchi" is made with salted baechu filled with thin strips of radish, parsley, pine nuts, pears, chestnuts, shredded red pepper, manna lichen (석이버섯), garlic, and ginger.

South Koreans consume 40 pounds (18 kg) of kimchi per person annually,[8] and many credit their nation's rapid economic growth in part to eating the dish.[10] Kimchi is made of various vegetables and contains a high concentration of dietary fiber,[16][17] while being low in calories. One serving also provides over 50% of the daily recommended amount of vitamin C and carotene. Most types of kimchi contain onions, garlic, and chilli peppers, all of which are salutary. The vegetables used in kimchi also contribute to its overall nutritional value. Kimchi is rich in vitamin A, thiamine (B1), riboflavin (B2), calcium, and iron,[18][19] and contains lactic acid bacteria, among those the typical species Lactobacillus kimchii.[20][21][22]Health magazine named kimchi in its list of top five "World's Healthiest Foods" for being rich in vitamins, aiding digestion, and even possibly reducing cancer growth. [23][24] A 2005 South Korean study found, however, that when eaten in large quantities, kimchi may increase the risk of gastric cancer, particularly among people with certain genetic traits.[25]

A study conducted by Seoul National University found that chickens infected with the H5N1 virus, also called avian flu, recovered after eating food containing the bacteria found in kimchi. During the 2003 SARS outbreak in Asia many people believed that kimchi could protect against infection and while there was no scientific evidence to support this belief, kimchi sales rose by 40%.[26][8][15] In May 2009 the Korea Food Research Institute, Korea’s state food research organization, said they had conducted a larger study on 200 chickens, which supported the theory that it boosts chickens' immunity to the virus.[27]

Kimchi can be made with white radishes, mustard greens, scalions, or cucumbers. Kimchi is known to be a traditional side dish as it is almost always served along with other side dishes in most Korean family households and restaurants. Kimchi can be eaten alone or with white rice but it is also included in recipes of other traditional dishes, including porridges, soups, and rice cakes. (Jung, C.) Kimchi is also the basis for many derivative dishes such as kimchi stew (김치찌개; kimchi jjigae), kimchi pancake (김치부침개; kimchijeon), kimchi soup (김칫국; kimchiguk), and kimchi fried rice (김치볶음밥; kimchi bokkeumbap).

In 1996, Korea protested against Japanese commercial production of "kimchi" arguing that the Japanese-produced product (kimuchi) was different from kimchi (in particular, that it was not fermented). Korea lobbied for an international standard from the Codex Alimentarius, an organization associated with the World Health Organization that defines voluntary standards for food preparation for international trade purposes.[8][29] In 2001 the Codex Alimentarius published a voluntary standard defining kimchi as "a fermented food that uses salted napa cabbages as its main ingredient mixed with seasonings, and goes through a lactic acid production process at a low temperature", but which did not specify a minimum amount of fermentation nor forbid the use of additives.[30][third-party source needed]

Due to heavy rainfall shortening the harvesting time for cabbage and other main ingredients for kimchi in 2010, the price of kimchi ingredients and kimchi itself rose greatly. Korean newspapers described the rise in prices as a national crisis. Some restaurants stopped offering kimchi as a free side dish, which The New York Times compared to an American hamburger restaurant no longer offering free ketchup.[15] In response to the Kimchi price crisis, the South Korean government announced the temporary reduction of tariffs on imported cabbage to coincide with the Kimjang season.[31]

Since 2012, the Chinese government has effectively banned Korean kimchi exports to China through government regulations. Ignoring the standards of Kimchi outlied by the Codex Alimentarius, China defined kimchi as a derivative of one of its own cuisines, called Pao cai.[1] However, due to significantly different preparation techniques from Pao cai, kimchi has significantly more lactic acid bacteria through its fermentation process, which exceeds China's regulations.[2] Since 2012, commercial exports of Korean kimchi to China has reached zero, the only minor amounts of exports accounting for Korean kimchi exhibition events held in China.[3]

Kimjang, the tradition of making and sharing of kimchi that usually takes place in late autumn, was added to the UNESCO Representative List of the Intangible Cultural Heritage of Humanity. The practice of Kimjang reaffirms Korean identity and strengthens family cooperation. Kimjang is also an important reminder for many Koreans that human communities need to live in harmony with nature.[32]